1. Field of Invention
The present invention relates to a method and an apparatus for making a color filter used in an optical device, such as a liquid crystal display. The present invention also relates to a method and an apparatus for making a liquid crystal display having a color filter. Furthermore, the present invention relates to a method and an apparatus for making an electro-luminescent (EL) device for display using an electro-luminescent layer.
Also, the present invention relates to a method for discharging a material, and an apparatus for discharging thereof. Further, the present invention relates to electronic apparatus with a liquid crystal display device or an electro-luminescent device manufactured by the methods.
2. Description of Related Art
Currently, display devices, such as liquid crystal devices and EL devices, are increasingly used in the display sections of electronic devices, such as cellular phones and portable computers. Also recently, an increasing number of display devices are employing a full-color display. Full-color display in the liquid crystal devices is, for example, achieved by leading the light modulated by liquid crystal layers to pass through color filters. The color filters are formed by, for example, aligning dots of filter elements of red (R), green (G), and blue (B) in a predetermined configuration, such as a striped pattern, a deltoid pattern, or a mosaic pattern, on the surface of a substrate made of glass, plastic, or the like.
In order to achieve full-color display in an EL device, dots of red (R), green (G), and blue (B) electro-luminescent layers (EL layers) are aligned in a predetermined pattern, such as a striped pattern, a deltoid pattern, or a mosaic pattern, on the surface of a substrate made of glass, plastic, or the like. Each of the EL layers is then sandwiched by a pair of electrodes so as to form a pixel, and the voltage applied to these electrodes is controlled according to the individual pixels so as to make the pixels emit desired colors and to achieve full-color display.
Conventionally, patterning of the R, G, and B filter elements and patterning of the R, G, and B pixels of the electro-luminescent device have been performed by photolithography. However, photolithography is a complex and costly process because the process consumes a large amount of colored materials, photoresists, and the like.
In order to overcome these problems, the use of an inkjet method in which the filter element and electro-luminescent layers aligned in the dot-matrix are formed by discharging in a dot-matrix a filter material, an electro-luminescent material, or the like, has been suggested.
Referring to FIGS. 22A and 22B, a plurality of filter elements 303 arranged in a dot matrix are formed by means of an inkjet method in the inner regions of a plurality of panel regions 302 defined on the surface of a mother substrate 301, i.e., a large-size substrate made of glass, plastic, or the like.
Here, as shown in FIG. 22C, an inkjet head 306 having a nozzle line 305 including a plurality of nozzles 304 arranged in a row performs first-scanning a number of times (two times in FIG. 22B) relative to one panel region 302 as shown by arrows A1 and A2 in FIG. 22B. Meanwhile, during the first-scanning, ink, that is, a filter material, is selectively discharged from the plurality of nozzles 304 so as to form filter elements 303 at the desired positions.
The filter elements 303 are formed by arranging colors such as R, G, and B, in an appropriate pattern, such as a striped pattern, a deltoid pattern, or a mosaic pattern. The process of discharging ink using the inkjet head 306 shown in FIG. 22B is performed as follows: three of the inkjet heads 306, each of which discharges one of three colors from among R, G, and B, are prepared in advance; and these inkjet heads 306 are used sequentially to form a pattern of three colors, such as R, G, and B, on one mother substrate 301.
As for the inkjet head 306, generally, there is a variation between the amounts of ink discharged from the plurality of nozzles 304 constituting the nozzle line 305. Accordingly, the inkjet head 306 has an ink-discharge characteristic Q shown in FIG. 23A, for example, wherein the discharge amount is largest at the positions corresponding to both ends of the nozzle line 305, next largest at the position corresponding to the middle thereof, and least at the other positions.
Thus, when the filter elements 303 are formed using the inkjet head 306 as shown in FIG. 22B, dense lines are formed at positions P1 corresponding to the end portions of the inkjet head 306 and/or at positions P2 corresponding to the middle of the nozzle line, as shown in FIG. 23B, impairing uniformity of the in-plane light transmission characteristics of the color filter.
Accordingly, it is a feature of the present invention to provide a method and an apparatus for manufacturing an optical component which can make uniform the planar optical characteristics of the optical component, i.e., the light transmission characteristics of a color filter, the color display characteristics of a liquid crystal device, the light-emission characteristics of an electro-luminescent surface.
In achieving these features, the present invention provides a method for making a color filter with a plurality of filter elements aligned on a substrate. The method can include a step of moving one of a inkjet head and the substrate in a first-scanning direction relative to the other, wherein the inkjet head has a nozzle line including a plurality of nozzle groups each including a plurality of nozzles, a step of selectively discharging a filter material from the plurality of nozzles to form the plurality of filter elements, and a step of moving one of the inkjet head and the substrate in a second-scanning direction relative to the other so that at least a part of each nozzle group is capable of scanning the same section of the substrate in the first direction.
In accordance with the above-described method for making the color filter, each of the filter elements in the color filter is not formed by one first-scanning of the inkjet head, but instead each of the filter elements is formed into a predetermined thickness by being applied with ink n times from the plurality of nozzles belonging to different nozzle groups. Accordingly, even when there is a variation between the discharged amounts of ink among the plurality of nozzles, variations in the layer thickness among the plurality of filter elements can be avoided, and light transmission characteristics of the color filter can thereby be made uniform.
It is apparent that because the filter elements are formed by discharging ink from the inkjet head in the above-described method, complex processes such as those employing photolithography techniques are not required and the raw materials are efficiently consumed.
In the above-described method for making a color filter, one of the inkjet head and the substrate is moved relative to the other by a distance corresponding to an integral multiple of the length of one of the nozzle groups in the second-scanning direction.
In the above-described method for making a color filter, the nozzle line may be tilted relative to the second-scanning direction. The nozzle line is formed by arranging the plurality of nozzles in a line. When the nozzle line is arranged in a direction parallel to the second-scanning direction of the inkjet head, the distance between adjacent filter elements formed by the filter element material discharged from the nozzles, i.e., the element pitch, becomes equal to the distance between the adjacent nozzles constituting the nozzle line, i.e., the nozzle pitch.
If an element pitch equal to the nozzle pitch is desirable, the nozzle line need not be tilted, however such a case is rare. In most cases, the element pitch and the nozzle pitch are different. When the nozzle line is tilted relative to the second-scanning direction of the inkjet head, the distance of the nozzle pitch in the second-scanning direction can be adjusted to coincide with the element pitch. Note that although in such a case, the positions of the nozzles constituting the nozzle line are shifted in the first-scanning direction, discharge timing of the filter element material from each of the nozzles is adjusted to apply ink droplets from the nozzles to the desired positions.
In the above-described method for making a color filter, the second-scanning distance xcex4 may be set so as to satisfy the equation:
xcex4≈(L/n)cos xcex8
wherein L represents the length of the nozzle line, n represents the number of the nozzle groups, and xcex8 represents the angle defined by the nozzle line and the second-scanning direction. In this manner, the plurality of the nozzles in the inkjet head can be moved in the second-scanning direction according to the nozzle groups. As a result, when the nozzle line is divided into four nozzle groups, for example, all the sections of the substrate are scanned by four different nozzle groups.
In the above-described method for making a color filter, some of the nozzles located at each of two end portions of the nozzle line may be set so as not to discharge the filter element material. As described above in association with FIG. 23A, the ink-discharge distribution of a typical inkjet head changes at the two end portions of the nozzle line compared to other portions. The in-plane layer thickness of the filter element can be made uniform if the plurality of nozzles having the same ink-discharge distribution, excluding some of the nozzles at the two end portions of the nozzle line having significantly large variations, are used in the inkjet head having such ink-discharging distribution characteristics.
When the process is performed without using some of the nozzles located at the two end portions of the nozzle line as described above, the second-scanning distance xcex4 can be set so as to satisfy the equation:
xcex4≈(L/n)cos xcex8
wherein L represents the length of the nozzle line excluding the two end portions of the nozzle line at which the nozzles not discharging the filter material are located, n represents the number of nozzle groups, and xcex8 represents the angle defined by the nozzle line and the second-scanning direction.
Next, the color filter made by the method described above can be formed by arranging the filter elements in different colors, such as R (red), G (green), and B (blue), or C (cyan), Y (yellow), and M (magenta), in a predetermined planar pattern. In making such a color filter, a plurality of the inkjet heads, each discharging a filter material of one color selected from among these colors from the nozzle line, may be separately prepared, and the first-scanning step and the second-scanning step are sequentially repeated relative to the same substrate for each of the plurality of inkjet heads, separately.
In making the above-described color filter having the filter elements of different colors such as R, G, and B, or C, Y, and M, the inkjet head may be provided with a plurality of nozzle lines each discharging a filter material of a different color, and the first-scanning step and the second-scanning step may be performed using the inkjet head so as to simultaneously apply the filter elements of different colors onto the substrate.
The present invention also provides an apparatus for making a color filter with a plurality of filter elements aligned on a substrate. The apparatus has an inkjet head having a nozzle line comprising a plurality of nozzle groups, each including a plurality of nozzles, an ink supplying element for supplying a filter material to the inkjet head, a first-scan driving element for moving the inkjet head in a first-scanning direction relative to the other, a second-scan driving element for moving one of the inkjet head and the substrate in a second-scanning direction relative to the other, and a nozzle discharge controlling element for controlling the discharge of the filter material from the plurality of the nozzles. The inkjet head can further include a first-scan controlling element for controlling the operation of the first-scan driving element, and a second-scan controlling element for controlling the operation of the second-scan driving element, wherein one of the inkjet head and the substrate is moved in a second-scanning direction relative to the other so that at least a part of each nozzle group is capable of scanning the same section of the substrate in the first direction.
The present invention further provides a method for making a liquid crystal device. The liquid crystal device has a pair of substrates for enclosing liquid crystal, and a plurality of filter elements aligned on at least one of the substrates. And the method can include a step of moving one of a inkjet head and the substrate in a first-scanning direction relative to the other, wherein the inkjet head has a nozzle line comprising a plurality of nozzle groups each including a plurality of nozzles, a step of selectively discharging a filter material from the plurality of nozzles to form the plurality of filter elements, and a step of moving one of the inkjet head and the substrate in a second-scanning direction relative to the other so that at least a part of each nozzle group is capable of scanning the same section of the substrate in the first direction.
The present invention also provides an apparatus for making a liquid crystal device. The liquid crystal device can include a pair of substrates for enclosing liquid crystal, and a plurality of filter elements aligned on at least one of the substrates. And the apparatus can include an inkjet head having a nozzle line comprising a plurality of nozzle groups, each including a plurality of nozzles, an ink supplying element for supplying a filter material to the inkjet head, a first-scan driving element for moving the inkjet head in a first-scanning direction relative to the other, a second-scan driving element for moving one of the inkjet head and the substrate in a second-scanning direction relative to the other, and a nozzle discharge controlling element for controlling the discharge of the filter material from the plurality of the nozzles. The inkjet head can further include a first-scan controlling element for controlling the operation of the first-scan driving element, and a second-scan controlling element for controlling the operation of the second-scan driving element, wherein one of the inkjet head and the substrate is moved in a second-scanning direction relative to the other so that at least a part of each nozzle group is capable of scanning the same section of the substrate in the first direction.
The present invention also provides a method for making an electro-luminescent device. The device can include a plurality of pixels, each including an electro-luminescent layer, aligned on a substrate. And the method has a step of moving one of a inkjet head and the substrate in a first-scanning direction relative to the other, wherein the inkjet head has a nozzle line comprising a plurality of nozzle groups each including a plurality of nozzles, a step of selectively discharging an electro-luminescent material from the plurality of nozzles to form the plurality of filter elements, and a step of moving one of the inkjet head and the substrate in a second-scanning direction relative to the other so that at least a part of each nozzle group is capable of scanning the same section of the substrate in the first direction.
The present invention provides an apparatus for making an electro-luminescent device. The device can include a plurality of pixels, each including an electro-luminescent layer, aligned on a substrate. And the apparatus has an inkjet head having a nozzle line including a plurality of nozzle groups, each including a plurality of nozzles, an ink supplying element for supplying a electro-luminescent material to the inkjet head, a first-scan driving element for moving the inkjet head in a first-scanning direction relative to the other, a second-scan driving element for moving one of the inkjet head and the substrate in a second-scanning direction relative to the other, and a nozzle discharge controlling element for controlling the discharge of the filter material from the plurality of the nozzles. The inkjet head further including a first-scan controlling element for controlling the operation of the first-scan driving element, and a second-scan controlling element for controlling the operation of the second-scan driving element, wherein one of the inkjet head and the substrate is moved in a second-scanning direction relative to the other so that at least a part of each nozzle group is capable of scanning the same section of the substrate in the first direction.
The present invention further provides a control unit for controlling an inkjet head which is used in making an optical component that includes a plurality of color patterns aligned on a substrate. The control unit can include an inkjet head having a nozzle line having a plurality of nozzle groups, each including a plurality of nozzles, an ink supplying element for supplying a electro-luminescent material to the inkjet head, a first-scan driving element for moving the inkjet head in a first-scanning direction relative to the other, a second-scan driving element for moving one of the inkjet head and the substrate in a second-scanning direction relative to the other, and a nozzle discharge controlling element for controlling the discharge of the filter material from the plurality of the nozzles. The inkjet head can further include a first-scan controlling element for controlling the operation of the first-scan driving element, and a second-scan controlling element for controlling the operation of the second-scan driving element, wherein one of the inkjet head and the substrate is moved in a second-scanning direction relative to the other so that at least a part of each nozzle group is capable of scanning the same section of the substrate in the first direction.